DE10083498B4 - A method of producing a thin polycrystalline layer and an oxide superconducting element - Google Patents

Abstract

A method for producing a thin polycrystalline layer composed of oxide crystal grains whose crystal structure is a rare earth oxide type (C) described by any one of the following formulas: Y ₂ O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O _3, and Lu ₂ O ₃ coated on the film-forming surface of a polycrystalline substrate wherein the inclination angles of the grain boundary between respective crystal axes of different crystal grains are kept at an angle of 30 ° along the plane parallel to the film-forming surface of the polycrystalline substrate, the polycrystalline substrate being brought to a temperature in the range of 250 to 350 ° C, and an ion beam of Kr ⁺ or Xe ⁺ ions or a beam combined from these ions is generated from an ion source, the energy of the ion beam being in a range of between 125 eV and 175 eV, while the incident angle of the ion beam irradiating the film-forming surface of the polycrystalline substrate is set between 50 and 60 degrees to the normal direction of the ...

Description

TECHNICAL TERRITORY

The The present invention relates to a process for the preparation of a thin polycrystalline layer with a crystal structure of a rare Type of earth oxide (C) with a well oriented crystal orientation and a method for producing an oxide superconducting element, which has excellent superconducting properties and one which on the aforementioned thin comprises polycrystalline layer formed superconducting oxide layer.

STATE OF THE ART

The superconducting oxides discovered in recent years are good superconducting substances whose critical temperature is above the Temperature of liquid Nitrogen lies. However, many problems remain to be solved before Superconducting oxides are used as superconductors in practice can be. One of the problems is the low critical current density of the superconducting ones Oxidstoffe.

The Problem of low critical current density of the superconducting Oxidant comes mainly from the electrical anisotropy to the crystals of the superconducting Oxidstoffes own. It is known that the electrical conductivity the superconducting oxides in the directions of the a-axis and The b-axis of the crystal is high, but in the direction of the c-axis is low. To use a formed on a substrate It is therefore superconducting oxide layer as a superconducting element required, on a substrate, a superconducting oxide layer with a good crystal orientation and the a-axis or the b-axis of the crystal of the superconductive oxide with the intended one Direction of current flow to bring a line while the c-axis of the superconducting oxide with the other direction to one Line is brought.

So far, an approach has been used in which an intermediate layer having a good crystal orientation consisting of MgO, SrTiO ₃ or the like is formed on a substrate such as a metal strip by means of a nebulizer and a superconducting oxide layer is applied to the intermediate layer. However, the oxide superconducting film formed on such an intermediate layer by means of an atomizer has a critical current density (typically about 1,000 to 10,000 A / cm ² ), which is much lower than that of a single crystal substrate formed of such a substance superconducting oxide layer (typically several hundred thousand A / cm ² ). It is assumed that the reason for this problem is the following.

14 is a sectional view of a superconducting oxide element, which was prepared so that initially an intermediate layer 2 on a substrate made of a polycrystalline material, in the form of a metal strip or something similar 1 is formed by means of an atomizer, and then a superconducting oxide layer 3 on the intermediate layer 2 is applied with the atomizer. In the in 14 The structure shown is the superconducting oxide layer 3 in a polycrystalline state in which a plurality of crystal grains 4 are arbitrarily juxtaposed. Each of these crystal grains 4 shows that the c-axis of each crystal is oriented perpendicular to the surface of the substrate, but the a-axis and the b-axis have an arbitrary orientation.

If the a-axes and the b-axes in the crystal grains of the superconducting oxide layer arbitrarily aligned are, deteriorate the superconducting properties, in particular the critical current density, since the quantum coupling of the superconducting State in the grain boundaries in which the crystal orientation is disturbed, get lost.

It is assumed that the reason why the oxide superconducting element comes into a polycrystalline state in which the a-axes and the b-axes are arbitrarily aligned is as follows: since the intermediate layer formed below the oxide superconducting element 2 has a polycrystalline structure with arbitrarily aligned a-axes and b-axes, the superconducting oxide layer would 3 be formed so that they match the crystal structure of the intermediate layer 2 equivalent.

For the inventors of the present invention, it has been found that an oxide superconducting element having a sufficient critical current density can be formed by forming on a polycrystalline substrate by a special method a YSZ (yttrium stabilized zirconia) intermediate layer containing well-aligned a and b -Axes and that a superconducting oxide layer is applied to the intermediate layer. With respect to this technology, the inventors have filed various applications, namely Japanese Unexamined Patent Application, First Publication No. Hei 4-293464, Japanese Patent Application, First Publication No. Hei 8-214806, Japanese Unexamined Patent Application, First Publication No. Hei 8-272606 and Japanese Unexamined Patent Application, First Publication No. Hei 8-272607.

The teaching proposed in these patent applications makes it possible, when forming a thin film on a polycrystalline substrate using a YSZ target, to selectively remove YSZ crystals having an unfavorable crystal orientation by an ion beam assisted process, in which process the film-forming surface of the polycrystalline substrate is obliquely irradiated with an ion beam such as Ar ⁺ , whereby YSZ crystals with a good crystal orientation are selectively deposited, resulting in the formation of an intermediate layer of YSZ crystals with a good crystal orientation.

To that proposed in the previous applications of the inventors Teaching can be a thin one Polycrystalline layer of YSZ with favorably aligned a- and B-axes are produced. It was also ensured that the one on the thin one Polycrystalline layer formed superconducting oxide sufficient has critical current density, and the inventors began to follow suit a further development of this teaching for the improvement of thin polycrystalline Layers of other substances to research.

15 Fig. 12 is a sectional view of an example of a superconductive oxide element recently used by the inventors. A superconductive oxide element D embodied according to this example has a four-layer structure which results from the fact that, by means of the teaching described at the outset, initially an intermediate layer consisting of YSZ or MgO 6 for orientation control on a substrate having the shape of a metal strip 5 is formed, then an intermediate layer consisting of Y 2 O ₃ 7 to stop the reaction is applied thereto, and in turn a superconducting oxide layer 8th is formed.

The reason why the four-layer structure is used is that in order to obtain a superconducting oxide film of composition Y ₁ Ba ₂ Cu _{7 -x} , it is necessary to form the superconducting oxide film having the desired composition by sputtering or other film-forming method to perform a heat treatment at a temperature of several hundred degrees Celsius, but the elements between the superconducting oxide layers having the compositions YSZ and Y ₁ Ba ₂ Cu ₃ O _7-x can diffuse due to the heat occurring during the heat treatment; Diffusion can degrade the superconducting properties and must be prevented. The YSZ crystals, which are the intermediate layer 6 for orientation control, have a cubic crystal structure, and the superconducting oxide layer of composition Y ₁ Ba ₂ Cu ₃ O _7-x has a perovskite called crystal structure. Both crystal structures belong to a class of cubic face-centered crystals and have similar crystal lattices, with a difference of about 5% between the lattice sizes of the two structures. For example, the distance between the nearest atoms, namely the distance between an atom at a corner of the cubic lattice and an atom at the center of the cubic lattice surface, is 3.63 Å (0.363 nm) for YSZ, 3.75 Å (0.375 nm) ) for Y ₂ O ₃ and 3.81 Å (0.381 nm) for an oxide superconducting layer of composition Y ₁ Ba ₂ Cu ₃ O _7-x . Thus, Y ₂ O _{3 has} a value intermediate between those of YSZ and Y ₁ Ba ₂ Cu ₃ O _7-x , is helpful for bridging the difference in the lattice size, and may advantageously be due to the similarity in the compositions as the reaction stopping layer be used.

With the in 15 However, the four-layer structure shown increases the number of layers required, which causes the problem that the number of manufacturing processes must be increased.

For forming a reaction stopping intermediate layer 7 consisting of favorably oriented Y ₂ O ₃ crystals directly on the formed as a metal strip substrate 5 the inventors tried the reaction stopping intermediate layer 7 on the substrate 5 apply the ion beam assisted process submitted in a previous application. The reaction-stopping intermediate layer 7 however, consisting of low orientation Y ₂ O ₃ crystals could not be formed under the layer forming conditions of a conventional ion beam assisted process.

In the meantime, techniques have been developed for forming various well-oriented layers on polycrystalline substrates in fields other than the use of superconductive oxides such as thin optical layers, magneto-optic disks, circuit boards, high frequency conductor waves, high frequency filters, and cavity resonators. In each of these areas, it is still a challenge, one favorably oriented thin polycrystalline layer with a stable layer quality on a substrate. A thin polycrystalline layer having a satisfactory crystal orientation would enable the quality of optical thin films, magnetic films or thin films for circuits to be applied thereto to be improved. The ability to form thin optical layers, thin magnetic layers or thin layers for circuits directly on the substrate with a satisfactory crystal orientation will be highly preferred.

PRESENTATION THE INVENTION

The invention is intended to solve the problems described above and has been completed after the inventors disclosed the methods for forming on a substrate disclosed in an earlier patent application, using ion beam assisted technology, a rare earth oxide type polycrystalline layer (C) such as Y ₂ O. ₃ had studied intensively with a favorable crystal orientation. The object of the present invention is to provide a process for producing a thin polycrystalline layer having rare earth oxide type (C) crystal grains such as Y ₂ O ₃ having a favorable crystal orientation which enables the c-axes of the oxide crystal grains of the rare earth oxide type (C) at right angles to the substrate surface on which the thin film is to be formed, and aligning the a and b axes of the rare earth oxide type crystal grains (C) on a plane parallel to the film forming surface of the substrate. Another object of the present invention is to provide a method for producing an oxide superconducting element comprising a polycrystalline substrate and a thin polycrystalline layer formed on the film-forming surface of the polycrystalline substrate, and an oxide superconducting layer formed on the above-mentioned thin polycrystalline layer includes.

The solution to the above-described problems is that the thin polycrystalline layer of the present invention consists essentially of oxide crystal grains having a rare earth oxide type crystal structure (C) represented by one of the following formulas: Y ₂ O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , He ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ and applied to the film-forming surface of a polycrystalline substrate, wherein the inclination angles of the grain boundary (the displacement angle of the grain boundary) between the same crystal axes of the various crystal grains in the thin polycrystalline layer along the plane parallel to the film-forming surface of the polycrystalline substrate in a plane Angle of 30 °, wherein the polycrystalline substrate is brought to a temperature in the range of 250-350 ° C, and an ion beam of Kr ⁺ or Xe ⁺ ions or a beam combined from these ions is generated from an ion source, the energy of the ion beam being set in a range between 125 eV and 175 eV, while the angle of incidence of the ion beam irradiating the layer-forming surface of the polycrystalline substrate is between 50 and 60 degrees to the normal direction of the film-forming surface of the polycrystalline substrate, when the particles formed by the target consisting of the same elements as the thin polycrystalline layer are deposited on the polycrystalline substrate.

The aforementioned polycrystalline substrate may be made of a Ni-alloy heat-resistant metal ribbon, and the above-mentioned thin polycrystalline layer may be Y ₂ O ₃ .

One Another object of the present invention is to provide a method for To provide a superconducting oxide element, the polycrystalline substrate, which after the aforementioned Process is made. Furthermore, the method according to the invention comprises a thin, on the film-forming surface polycrystalline substrate formed polycrystalline layer and one on the thin one polycrystalline layer formed superconducting oxide layer, wherein these after depositing the thin ones polycrystalline layer is formed.

The rare earth oxide type (C) thin polycrystalline layer (C) such as Y ₂ O ₃ formed on the polycrystalline substrate is more advantageous than the conventional thin film of YSZ in many respects when a superconducting layer consisting of an oxide is deposited thereon.

First, the lattice constant of ZrO ₂ , which is the main constituent of the YSZ crystal, is 5.14 Å (0.514 nm), and it is assumed that the distance between an atom located in the center of the surface of the unit cell and one in the corner of the unit cell Atom (the distance between nearest atoms) in the face centered cubic lattice of ZrO _{2 is} 3.63 Å (0.363 nm), then the lattice constant of the Y ₂ O ₃ crystal is 5.3 Å (0.53 nm) and the distance between the nearest atoms 3.75 Å (0.375 nm). Considering that the distance between the nearest atoms of a superconductive oxide of composition Y ₁ Ba ₂ Cu ₃ O _{7-x is} 3.9 Å (0.39 nm), and that the lattice constant is between 5.4 and 5.5 Å (0.54 to 0.55 nm), which is ^2½ (the square root of 2) times the size of 3.9 Å (0.39 nm), Thus, the thin polycrystalline layer of Y ₂ O ₃ with respect to the crystal equivalent appears more advantageous than the thin polycrystalline layer of YSZ. That is, as the atoms of the thin polycrystalline layer are deposited by the ion beam assisted method, normal deposition of the atoms using a material having a smaller distance between the nearest atoms could be more easily achieved. In addition, since Y ₂ O _{3 has} a rare earth oxide type crystal structure (C), a substance having a rare earth oxide type crystal structure (C) and having one of the following compositions Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ .

The research conducted by the inventors has revealed that BaZrO _{3 is} likely to be formed by thermal diffusion due to the heat generated during the manufacturing process or due to heat treatment at the interface between the thin polycrystalline YSZ layer and the superconducting oxide layer of Y ₁ Ba ₂ Cu ₃ O _7-x can be generated while the interface between the polycrystalline Y ₂ O ₃ thin film and the Y ₁ Ba ₂ Cu ₃ O _7-x superconducting oxide layer is stable under heat conditions at temperatures between about 700 to 800 ° C, whereby a thin polycrystalline Y ₂ O ₃ layer is also promising in this regard.

According to the present invention, the thin rare earth oxide type crystal grains (C) such as Y ₂ O _{3 may} have a favorable crystal orientation and be formed on the polycrystalline substrate at 30 degree inclination angles of the grain boundary (the grain boundary displacement angle) , preferably serve as a base for forming various thin layers on this layer, and enables to obtain good superconducting properties in the case where the thin layer to be formed is a superconducting layer, to obtain good optical properties in the case where the thin layer to be formed is an optical layer, obtaining good magnetic properties in the case where the thin layer to be formed is a magnetic layer, and obtaining a thin layer having a lower switching resistance and fewer errors in the case of the thin one layer to be formed for Switching plates is used.

The rare earth oxide type oxide (C) used in the thin polycrystalline layer may be an oxide of any one of the following compositions: Y ₂ O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , He ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ .

A Ni-alloy heat-resistant metal tape may be used as the polycrystalline substrate, and a metal tape carrying the thin polycrystalline layer-containing crystal grains of a rare earth oxide type (C) such as Y ₂ O ₃ may be fabricated.

Since, in the deposition of the particles generated by the Y ₂ O ₃ target on the polycrystalline substrate, the substrate is maintained in a temperature range between 250 to 350 ° C, the energy of the ion beam is set between 125 eV and 175 eV, and the angle of incidence of the Substrate irradiating ion beam is between 50 and 60 degrees to the normal direction of the film-forming surface, the thin polycrystalline Y ₂ O ₃ layer can be formed directly with a good crystal orientation on the polycrystalline substrate, which was impossible in the prior art.

Since the thin polycrystalline Y ₂ O ₃ layer can be formed directly on the polycrystalline substrate, further coating with a thin polycrystalline YSZ layer is not necessary and the number of times required for forming a satisfactory layer having good crystal orientation on a polycrystalline substrate Layers is reduced, which contributes to the simplification of the manufacturing process.

When the superconducting oxide film is formed on the thin polycrystalline Y ₂ O _{3 film} provided with good crystal orientation as described above, a superconducting oxide film having a good crystal orientation can be formed, thereby forming a superconducting oxide film having a high critical current density and a high critical current can be produced. The reason for this is the better crystal matching properties to the superconducting oxide layer of the thin polycrystalline Y ₂ O ₃ layer compared to the thin polycrystalline YSZ layer, making it possible to fabricate a superconducting oxide layer having a better crystal orientation than that using a thin polycrystalline YSZ layer is possible.

Moreover, since the thin polycrystalline Y ₂ O ₃ layer is formed directly on the polycrystalline substrate can be, the number of layers constituting the oxide superconducting element can be reduced, resulting in a simplification of the manufacturing process as compared with the prior art, in which, taking into account the heat treatment after the formation of the superconducting oxide layer, a double layer from YSZ and Y ₂ O ₃ is used.

After the investigations conducted by the inventors, it has been found that BaZrO _{3 is} likely to be generated in the interface between the YSZ polycrystalline thin film and the Y ₁ Ba ₂ Cu ₃ O _7-x superconducting oxide layer by thermal diffusion due to heat treatment or the like However, with the interface between the thin polycrystalline Y ₂ O ₃ layer and the superconducting oxide layer Y ₁ Ba ₂ Cu ₃ O _{7 -x} stable under the heat conditions at a temperature between 700 and 800 ° C, the thin polycrystalline Y _{2 is} O ₃ layer is also advantageous in this respect, and makes it possible to provide a superconductive oxide element which, even when subjected to a heat treatment after formation of the oxide superconducting layer, is less susceptible to deterioration of superconducting properties.

SHORT DESCRIPTION THE DRAWING

1 Fig. 10 is a partial sectional perspective of an example of a thin polycrystalline layer formed by the method of the present invention.

2 FIG. 12 is an enlarged plan view showing the crystal grains of the thin polycrystalline layer 1 , which shows orientation of their crystal axes and the inclination angle of the grain boundary (the displacement angle of the grain boundary).

3 is a schematic representation of the crystal lattice of a thin polycrystalline Y ₂ O ₃ layer.

4 Fig. 10 is a schematic illustration of an example of a method for producing the thin polycrystalline layer.

5A is a schematic representation of an example of an ion source for the device from 4 ,

5B is a schematic representation of the angle of incidence of the ion beam.

6 is a schematic representation of one on the thin polycrystalline layer 1 formed superconducting oxide layer.

7 Fig. 12 is an enlarged plan view of the crystal grains of the oxide superconducting layer 6 , the orientation of their crystal axes and the inclination angle of the grain boundary (the displacement angle of the grain boundary).

8th Fig. 12 is a schematic illustration of an example of an apparatus for forming a superconducting oxide layer on the thin polycrystalline layer 1 ,

9 FIG. 12 is a polar diagram of a thin polycrystalline Y ₂ O ₃ film produced in the embodiment. FIG.

10 FIG. 14 shows the relationship between the substrate temperature and the Y ₂ O ₃ (400) peak in the thin polycrystalline Y ₂ O ₃ film produced in the embodiment.

11 shows the relationship between the energy of the ion beam and the Y ₂ O ₃ ( 400 ) Tip in the thin polycrystalline Y ₂ O ₃ layer produced in the embodiment.

12 FIG. 12 is an X-ray spectrograph showing the (400) tip in the polycrystalline Y ₂ O _{3 film obtained} in the embodiment. FIG.

13 FIG. 12 shows the relationship between the angle of incidence of the ion beam and the crystal orientation during the production of the polycrystalline Y ₂ O ₃ film produced in the embodiment.

14 is a schematic representation of a thin polycrystalline layer, with a Vorrich tion was made according to the prior art.

15 shows in a sectional view an example of a previously known oxide superconducting element.

EMBODIMENTS THE INVENTION

Based the attached Drawings will become a preferred embodiment of the present invention below described.

1 shows an embodiment in which a thin polycrystalline layer has been formed according to the manufacturing method of the invention on a substrate in which A denotes a ribbon-shaped polycrystalline substrate, and B indicates a thin polycrystalline layer formed on the surface of the polycrystalline substrate A.

The polycrystalline substrate A may have various shapes, such as for example, a sheet, a wire or a tape. The polycrystalline substrate A is made of a metal or of an alloy such as e.g. Silver, Platinum, Stainless Steel, Copper, Hastelloy or another Ni alloy, or a non-metallic material such as. Glass or ceramics.

The thin polycrystalline layer B of this embodiment is composed of numerous fine crystal grains consisting of Y ₂ O ₃ having a rare earth oxide type crystal structure (C) of an isometric system 20 formed on the grain boundaries are stored together, wherein the c-axis of each crystal grain 20 perpendicular to the surface of the substrate A (the surface on which the layer is to be formed), while the a-axes, as well as the b-axes of the individual crystal grains 20 have the same direction and are aligned in the substrate surface. The c-axis of each crystal grain 20 is also aligned perpendicular to the surface of the polycrystalline substrate A, on which the layer is to be formed (top surface). The grains are attached in such a way that the angle (in 2 shown inclination angle K of the grain boundary) between the a-axes (b-axes) of various crystal grains 20 is limited to 30 degrees, for example, in a range of 25 to 30 degrees.

As an oxide for producing the crystal grains 20 oxides of a rare earth oxide type (C) may be used, such as Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ and Lu ₂ O ₃ .

While the crystal lattice of Y ₂ O ₃ belongs to a rare earth oxide type (C), the rare earth oxide type (C) is derived from a fluorite structure of a cubic crystal system and has a structure such that when eight elementary cells of a face centered cubic structure as shown in FIG 3 is shown lying in an oblong and lateral direction, only one of the oxygen atoms which have occupied the interstices between the Y-atoms existing lattice is removed. Therefore, a block of eight stacked Y ₂ O ₃ lattices is considered as one unit cell in the X-ray analysis, and therefore the lattice constant of the unit cell is 10.6 Å (1.06 nm) the unit cell width, 5.3 Å (0.53 nm) and the distance between the nearest atoms, 3.75 Å (0.375 nm).

If ₃ crystals are deposited under conditions with an ion beam assisted method Y ₂ O, which are described later, is an important factor, the distance between the nearest atoms, namely 3.75 Å (0.375 nm) and preferably nearer to the distance between the nearest atoms, which is 3.81 Å (0.381 nm) in lattice constant 3.81 Å, and the distance between the nearest atoms, which is 3.81 Å (0.381 nm), in the oxide superconducting layer of composition Y ₁ Ba ₂ Cu ₃ O _7-x. The difference between the distance between the nearest atoms and that of the superconducting layer having the composition Y ₁ Ba ₂ Cu ₃ O _7-x is 1.5% for Y ₂ O ₃ , but is 4.5% for YSZ whose distance between the nearest atom is 3.63 Å (0.363 nm).

Other rare earth oxide type (C) oxides which can also be used are: Sc ₂ O ₃ , whose lattice constant is 9.84 Å, and where the distance between the nearest atoms is 3.48 Å (0.348 nm); Nd ₂ O ₃ , whose lattice constant is 11.08 Å, and where the distance between the nearest atoms is 3.92 Å (0.392 nm); Sm ₂ O ₃ , whose lattice constant is 10.972 Å, and where the distance between the nearest atoms is 3.86 Å (0.386 nm); Eu ₂ O ₃ , whose lattice constant is 10.868 Å, and where the distance between the nearest Atoms is 3.84 Å (0.384 nm); Gd ₂ O ₃ , whose lattice constant is 10.813 Å, and where the distance between the nearest atoms is 3.82 Å (0.382 nm); Tb ₂ O ₃ , whose lattice constant is 10.73 Å, and where the distance between the nearest atoms is 3.79 Å (0.379 nm); Dy ₂ O ₃ , whose lattice constant is 10.665 Å, and in which the distance between the nearest atoms are 3.77 Å (0.377 nm); Ho ₂ O ₃ , whose lattice constant is 10.606 Å, and where the distance between the nearest atoms is 3.75 Å (0.375 nm); Er ₂ O ₃ , whose lattice constant is 10.548 Å, and where the distance between the nearest atoms is 3.73 Å (0.373 nm); Yb ₂ O ₃ , whose lattice constant is 10.4347 Å, and where the distance between the nearest atoms is 3.69 Å (0.369 nm); and Lu ₂ O ₃ whose lattice constant is 10.39 Å and where the distance between the nearest atoms is 3.67 Å (0.367 nm).

A Apparatus for producing the thin polycrystalline layer B and a method for producing the same will be described below described.

4 shows an example of the device for producing the thin polycrystalline layer B, the structure of which is such that an ion source for the ion beam assisted operation is provided on a nebulizer.

In this example, the device comprises: a separation tank 40 in which a vacuum can be pumped and a substrate holding device 23 which holds the ribbon-shaped polycrystalline substrate A and, meanwhile, can bring it to the desired temperature; a substrate donating role 24 for feeding the polycrystalline substrate A to the substrate holding device 23 ; a substrate receiving roll 25 for winding the polycrystalline substrate A thereon where the thin polycrystalline layer has been formed; a plate-shaped target 36 slanting above and opposite to the substrate holding device 23 is kept at a distance; a device for generating a spray jet 38 that is obliquely above the target 36 and arranged facing this; and an ion source 39 laterally opposite the substrate holding device 23 is kept at a distance, and also from the target 36 is spaced contains.

In the substrate holding device 23 is a heater for heating the substrate holding device 23 provided in the form of a tape supplied polycrystalline substrate A to the desired temperature. The substrate holding device 23 is by means of a pin or something similar on a support base 23a mounted so that it is free to pivot, whereby its inclination angle can be adjusted. The substrate holding device 23 is in an optimal radiation range from that of the ion source 39 within the separator tank 40 generated ion beam arranged.

In this apparatus for producing the thin polycrystalline layer, the substrate donating role 24 continuously the band-shaped polycrystalline substrate A of the substrate holding device 23 to, and the substrate take-up roll 25 wraps the polycrystalline substrate A where the thin polycrystalline layer has been formed in the optimum radiating region, whereby the thin polycrystalline layer is continuously formed on the polycrystalline substrate A. The substrate pickup roller 25 is located outside the optimum radiation range.

The target 36 is intended to form the desired thin polycrystalline layer and consists of a material of the same or a similar composition as that of the thin polycrystalline layer. In particular, there is the target 36 from CeO ₂ . The target 36 gets onto a target holder 36a mounted, which rotates freely by means of a pin or something similar, while the inclination angle can be adjusted.

The jet-generating atomizer device (atomizer) 38 is constructed such that an evaporation source is accommodated in a container, and that a grid for applying a voltage is mounted in the vicinity of the evaporation source, so that the target 36 is irradiated with an ion beam, the particles from the target 36 abträgt and this leads to the polycrystalline substrate A.

The ion source 39 is substantially similar to the beam generating atomizer device 38 wherein an arbitrary source of evaporation is accommodated in a container and a grid for applying a voltage is mounted in the vicinity of the evaporation source. Part of the atoms and molecules vaporized in the evaporation source are ionized, and the ionized particles are controlled by the electric field generated by the grid and condensed into an ion beam. The particles can be ionized by various methods, such as by direct current discharge, high frequency excitation, filament heating and a cluster ion beam method. The filament heating method generates thermal electrons by the heat generated by the flow of an electric current through a tungsten filament and causes them to strike the high-vacuum evaporated particles, thereby ionizing these particles. With the cluster ion beam method, a molecular cluster provided from a nozzle provided in an opening of a crucible containing an evaporation source becomes is injected into a vacuum, hit by thermal electrons, whereby it is ionized and irradiated.

In the apparatus for producing the thin polycrystalline layer described at the outset, the ion source becomes 39 used, which is executed inside, as in 5A shown. The ion source 39 includes a cylindrical ionization chamber 45 that a grid 46 , a filament 47 , and an inlet pipe 48 for introducing gas such as Kr or Xe, and may contain ions in a substantially parallel beam from a jet port provided at the distal end of the ionization chamber 49 send out.

As in 4 the ion source is shown 39 arranged such that its center line S at an angle of incidence 8th (the angle between the normal direction of the film-forming surface of the polycrystalline substrate A and the center line S) is inclined. The angle of incidence θ is between 50 and 60 degrees, in a preferred embodiment between 55 and 60 degrees, and in the most preferred variant about 55 degrees. Thus, the ion source 39 arranged so that it the layer-forming surface of the polycrystalline substrate A with the ion beam at an angle of incidence 8th irradiated to the normal direction H. The inventors have filed an earlier patent application dealing with the angle of incidence of the ion beam.

For that of the ion source 39 On the polycrystalline substrate A directed ion beam Kr-gas or Xe gas or a mixture of can be used.

The separation tank 40 is with a rotary pump 51 and a cryopump 52 with which the interior of the container 40 is placed in a vacuum state, and provided with an associated source of atmospheric gas such as a gas cylinder, so that the emptied interior of the separation vessel 40 can be filled with a noble gas such as argon.

The separation tank 40 is further provided with a current density meter for measuring the current density of the ion beam in the container 40 and with a pressure gauge 55 for measuring the in the container 40 equipped with the prevailing pressure.

While the thin polycrystalline layer-generating device of this example is constructed so that the substrate holding device 23 freely pivotable on the support base 23a is mounted by means of a pin or the like and that its inclination angle can be adjusted, the angle of incidence of the ion beam can also be adjusted by applying an angle adjustment mechanism to the support base of the ion source 39 is installed, the angle of inclination of the ion source 39 established. It is understood that the angle adjustment mechanism is not limited and that various embodiments can be used.

Hereinafter, an operation will be described for the case where the thin polycrystalline Y ₂ O ₃ layer B is formed on the polycrystalline substrate A using the apparatus in the above-described embodiment.

For forming the thin polycrystalline layer on the belt-shaped polycrystalline substrate A, a target consisting of Y ₂ O ₃ is formed 36 used; while the interior of the separation tank 40 in which the polycrystalline substrate A is housed, is pumped out to generate a low pressure, the polycrystalline substrate A becomes a substrate-donating roller at a predetermined speed 24 on the substrate holding device 23 guided, and the ion source 39 and the jet-generating atomizer device 38 Are operated.

If the target 36 with the one-beam atomizing device 38 When the generated beam is irradiated, particles are emitted from the target 36 abraded and impinge on the polycrystalline substrate A. Then those from the target 36 ablated particles on the substrate holder 23 deposited polycrystalline substrate A deposited and simultaneously with an ion beam from, for example, from the ion source 39 Kr ⁺ and Xe ⁺ ions produced or irradiated from a combination of Kr ⁺ and Xe ⁺ ions, thereby forming a thin polycrystalline layer of a desired thickness, while the band-shaped polycrystalline substrate A carrying the thin layer impinges on the substrate receiving roll 25 is wound.

The angle of incidence θ of the ion beam irradiation is between 50 and 60 degrees, in a preferred embodiment between 55 and 60 degrees, and in the most preferred embodiment about 55 degrees. When θ is 90 degrees, the c-axis of the thin polycrystalline layer can not be oriented. When θ is 30 degrees, the orientation of the c-axis of the thin polycrystalline layer can not be achieved. When the ion beam is incident in an angle of incidence in the above-described range, the c-axis is the thin aligned polycrystalline Y ₂ O ₃ layer in the vertical direction. When the ion beam irradiation is performed at such an angle of incidence, the a axes of the various grains of the thin polycrystalline Y ₂ O _{3 film} formed on the polycrystalline substrate A are aligned in the same direction and in a plane parallel to the surface (film forming layer) Surface) of the polycrystalline substrate A; the same applies to the b-axes.

In forming the rare earth oxide type thin polycrystalline layer B (C) such as Y ₂ O ₃ , in addition to controlling the incident angle of the assisting ion beam, it is necessary to have the temperature of the polycrystalline substrate A and the energy of the assisting ion beam in respective regions to keep.

The Temperature of the polycrystalline substrate A is in a particular preferred embodiment between 250 and 350 ° C and in a particularly preferred embodiment at 300 ° C.

The Energy of the ion beam is between 125 and 175 eV and in one particularly preferred embodiment at 150 eV.

The thin polycrystalline layer B of a rare earth oxide type (C) such as Y ₂ O ₃ can only be formed with a good orientation if it is supported on the polycrystalline substrate A by means of an ion beam assisted process with a temperature and ion beam energy moving in these regions is formed.

The 1 and 2 show the polycrystalline substrate A, on which the thin polycrystalline Y ₂ O ₃ layer B was formed by the method described above. Even though 1 shows a case in which a single layer of crystal grains 20 The crystal grains can be made 20 can also be deposited in many layers.

The inventors believe that the reason that the crystal orientation of the thin polycrystalline layer B is aligned is as follows: The crystal lattice of the Y ₂ O ₃ thin polycrystalline layer B has a rare earth oxide type structure (C) of a cubic face-centered system an isometric crystal structure as in 5B with the normal direction of the substrate being on the <100> axis with the remaining <010> and <001> axes aligned as it is 5B can be seen. In studying the incidence of the ion beam at an angle to the normal direction of the substrate with respect to these directions, it turns out that the incident angle is 54.7 degrees when the beam in the diagonal direction of the elementary grating is caused by the origin O in 5B , ie guided along the axis <111>. The reason that good crystal orientation is achieved when the angle of incidence is between 50 and 60 degrees, as described above, is possibly that when the ion beam is incident at an angle of about 54.7 degrees, the ions are channeled most effectively such that only those atoms are capable of remaining stabilized at an angle corresponding to this on the upper surface of the polycrystalline substrate A, while the other unstable atoms which are in a disordered atomic arrangement are atomized and removed by the ion beam become. It follows that only those crystals are left for the deposition, which consist of well-oriented atoms. It should be noted, however, that the ion beam sputtering effect accompanying the ion beam channeling is effectively achieved with an ion beam of Kr ⁺ ions or Xe ⁺ ions or an Xe ⁺ and Kr ⁺ ion beam for the thin polycrystalline Y ₂ O ₃ layer can.

Even if the thin polycrystalline Y ₂ O ₃ layer B was formed under the conditions described above, a satisfactory channeling effect of the ion beam can be achieved only when the temperature of the polycrystalline substrate A during film formation and the energy of the ion beam during the ion beam assisted process lie in the areas described above. Therefore, in the formation of the film, it is necessary to keep all three parameters, such as the angle of incidence of the ion beam, the temperature of the polycrystalline substrate A, and the energy of the ion beam, in the appropriate ranges.

Now on the 6 and 7 Reference is made, which is an embodiment of a superconducting oxide element according to the invention 22 demonstrate. The method for producing the oxide superconducting element 22 This embodiment comprises a polycrystalline substrate A having a shape of a sheet, a thin polycrystalline layer B formed on the surface of the polycrystalline substrate A, and an oxide superconducting layer C formed on the surface of the polycrystalline thin film B.

The polycrystalline substrate A and the thin polycrystalline layer B are made of the same materials as those described in the foregoing example, and crystal grains 20 of the thin polycrystalline layer B are oriented so that the inclination angles of the grain boundary are not larger than 30 degrees, and preferably between 25 and 30 degrees, as shown in FIGS 1 and 2 can be seen.

The formed oxide superconducting layer C covers the surface of the thin polycrystalline Y ₂ O ₃ layer B, with the c-axes of the crystal grains 21 are aligned perpendicular to the surface of the thin polycrystalline layer B, while the a-axes and the b-axes of the crystal grains 21 in a plane parallel to the surface of the substrate in a similar manner as in the case of the above-described thin polycrystalline layer B, and the inclination angles K 'of the grain boundary between the crystal grains 21 be kept at an angle of 30 degrees.

The oxide superconducting material constituting the oxide superconducting layer is a high critical temperature superconductive oxide material having one of the following compositions Y ₁ Ba ₂ Cu ₃ O _7-x , Y ₂ Ba ₄ Cu ₈ O _x or Y ₃ Ba ₃ Cu ₆ O _x , (Bi, Pb) ₂ Ca ₂ Sr ₂ Cu ₃ O _x or (Bi, Pb) ₂ Ca ₂ Sr ₃ Cu ₄ O _x or TI ₂ Ba ₂ Ca ₂ Cu ₃ O _x , TI ₁ Ba ₂ Ca ₂ Cu ₃ O _x or TI ₁ Ba ₂ Ca ₃ Cu ₄ O _x , but it is also possible to use a superconductor of another oxide.

The oxide superconducting film C is formed on the polycrystalline thin film B by a film forming method such as sputtering or laser deposition, and the superconducting oxide film formed on the thin polycrystalline film B also has a crystal orientation corresponding to the orientation of the rare earth oxide thin film P polycrystalline film B. C), for example Y ₂ O ₃ . As a result, since the oxide superconducting layer formed on the thin polycrystalline layer B provides excellent quantum coupling in the grain boundaries and its superconducting properties in the grain boundaries hardly deteriorate, the polycrystalline substrate A has high current conductivity in the longitudinal direction and generates a sufficiently high critical Current density comparable to that of a superconducting oxide film obtained on a single crystal substrate such as MgO.

For producing the thin polycrystalline layer B, Y ₂ O _{3 is} better than YSZ, and the oxide superconducting element formed by forming the oxide superconducting layer on the thin polycrystalline Y ₂ O ₃ layer keeps high temperatures (700 to 800 ° C) in the Heat treatment is better than the superconducting oxide layer formed on the thin polycrystalline YSZ layer and has a satisfactory critical current density, which is similar to that of the superconducting oxide layer formed on the thin polycrystalline YSZ layer. In particular, as the film thickness increases, the critical current density decreases even after a heat treatment or the like less, so that the production of a superconductor having a high critical current becomes possible.

First, the thin polycrystalline Y ₂ O ₃ layer in which the distance between the nearest atoms to the superconducting oxide layer is closer than that of the thin polycrystalline YSZ layer is presumed to be the crystal equivalent more advantageous.

Secondly, the study conducted by the inventors has revealed that BaZrO ₃ is capable of being generated in the interface between the thin polycrystalline YSZ layer and the oxide superconducting layer Y ₁ Ba ₂ Cu ₃ O _7-x by thermal diffusion due to heat treatment or the like Nevertheless, the interface between the thin polycrystalline Y ₂ O ₃ layer and the superconducting oxide layer Y ₁ Ba ₂ Cu ₃ O _7-x under heating conditions to a temperature of about 700 to 800 ° C is stable, and a diffusion of the elements at this Interface hardly occurs. Thus, the thin polycrystalline Y ₂ O ₃ layer is also advantageous in view of this.

In addition, depending on the temperature, YSZ undergoes phase transformation from a cubic system to an orthorhombic system, while Y ₂ O ₃ does not undergo phase transformation and thereby has an advantage. Considering the bonding force to an oxygen atom, Y ₂ O ₃ tends more to bond with oxygen than YSZ, resulting in that the layer can satisfactorily be formed under a lower partial pressure of oxygen, thereby less stressing the device becomes, which is more promising.

The Apparatus for forming the oxide superconducting film C will be described below described.

8th Fig. 10 is an illustration of an example of an apparatus for forming the superconducting oxide layer and shows a laser separator.

The laser separator 60 This example has a treatment tank 61 in which a band-shaped polycrystalline substrate A and a target 63 in one in the treatment tank 61 provided deposition chamber 62 can be installed. In particular, it becomes a base 64 to the bottom of the deposition chamber 62 placed so that the polycrystalline substrate A is horizontal to the surface of the base 64 can be placed, and that by a holder 66 worn target 63 in an inclined state obliquely above the base 64 is arranged. The polycrystalline substrate A is from a drum-shaped tape dispenser 65a to the base 64 guided and is of a drum-shaped tape recording device 65a wound.

The treatment tank 61 is over an outflow opening 67a at a vacuum pumping station 67 connected so that the internal pressure can be lowered to a predetermined level.

The target 63 is a sheet composed of a sintered composite oxide or a superconducting oxide material having the same or a similar composition as the superconductive oxide layer C to be formed, or contains a higher concentration of a component that escapes during the layer formation.

The base 64 includes a heater for heating the polycrystalline substrate A to a desired temperature.

Side of the treatment chamber 61 are a laser device 68 , a first reflector 69 , a condenser lens 70 , and a second reflector 71 so that one from the laser device 68 generated laser beam via a in a side wall of the treatment container 61 provided transparent window 72 on the target 63 can be directed and hits it. As a laser device 68 For example, all types of lasers can be used, including a YAG laser, a CO ₂ laser, and an excimer laser, provided they include particles from the target 63 can ablate.

When next becomes an operation for forming the superconducting oxide layer C on the thin polycrystalline layer B described.

After the thin polycrystalline Y ₂ O ₃ layer B is formed on the polycrystalline substrate A, the superconducting oxide layer is formed on the thin polycrystalline layer B. In this embodiment, to form the superconducting oxide layer on the thin polycrystalline layer B, the in 8th shown laser separator 60 used.

The polycrystalline substrate A having the thin polycrystalline layer B formed thereon becomes the base 64 of in 8th shown Laserabscheidegeräts 60 placed, and the deposition chamber 62 is emptied by means of a vacuum pump. This can help create an oxygen atmosphere in the deposition chamber 62 Oxygen into the deposition chamber 62 be introduced. The in the base 64 Built-in heater is driven so that it heats the polycrystalline substrate A to the desired temperature.

Then the target becomes 63 in the deposition chamber 62 with that of the laser device 68 generated laser beam irradiated. As a result, the material that makes up the target becomes the target 63 is removed or it is vaporized and deposited on the thin polycrystalline layer B. Since the thin polycrystalline Y ₂ O ₃ layer B on which the particles have been deposited is in a state where the c-axis orientation has been made while the a and b axes are also oriented, an epitaxial growth of the crystals will occur is achieved in which the c-axes, a-axes and b-axes of the crystals of the superconducting oxide layer C formed on the thin polycrystalline layer B correspond to the thin polycrystalline layer B. Thus, a superconductive oxide film C having a satisfactory crystal orientation can be obtained.

The oxide superconducting layer C formed on the thin polycrystalline layer B is polycrystalline, although in the individual crystal grains of the oxide superconducting layer C, the c-axis having high electric conductivity is oriented in the direction of the thickness of the polycrystalline substrate A, and the a - or b-axes of different grains in the longitudinal direction of the polycrystalline substrate A are oriented. Since the superconductive oxide layer thus formed has good quantum coupling properties in the grain boundaries and less deteriorates its superconducting properties in the grain boundaries, the electrical conductivity in the directional plane of the polycrystalline substrate A and the critical current density are high. To stabilize the crystal orientation and the layer quality of the oxide superconducting layer C, it is preferable to heat-treat to a temperature of 700 to 800 ° C in the required period of time taken and then cooled. (Embodiments)

With the device for forming a thin polycrystalline layer in the embodiment according to 4 The separation vessel was evacuated to a pressure of 3.0 × 10 ^-4 Torr (399.9 × 10 ^-4 Pa) by means of a rotary pump and a cryopump. The substrate used was a 10 mm wide, 0.5 mm thick and 100 cm long, high gloss polished Hastelloy C276 tape. The target consisted of Y ₂ O ₃ . The atomization conditions were set as follows: a sputtering voltage of 1000 V, a sputtering current of 100 mA, the incident angle of the ion source-generated Kr ⁺ ion beam to the normal direction of the film-forming substrate surface being 55 degrees, the ion beam traveling 40 cm, an ion source auxiliary voltage 150 eV, a current density of the ion source is 100 μA / cm ² , the temperature of the substrate tape is 300 ° C, and the oxygen release to the air is 1 × 10 ^-4 Torr (133.3 × 10 ^-4 Pa); were there. deposited the target particles on the substrate and simultaneously formed the thin polycrystalline Y ₂ O ₃ layer by irradiation with the ion beam in a thickness of 1.0 microns.

Based on an X-ray diffraction analysis of the thin polycrystalline Y ₂ O _{3 film obtained} by a θ-2θ method using the CuK "line, as in 9 shown a polar plot with respect to the <200> direction of Y ₂ O ₃ drawn. From the in 9 As shown in the polar diagram, it can be seen that the thin polycrystalline Y ₂ O ₃ layer B has a satisfactory crystal orientation. From the in 9 As shown in the polar diagram, an inclination angle of the grain boundary of 27 degrees was determined for the thin polycrystalline Y ₂ O ₃ layer.

Then, the film-forming conditions for the thin polycrystalline Y ₂ O _{3 film were} examined by testing the orientation of the thin Y ₂ O ₃ polycrystalline film obtained by changing the energy of the Ar ⁺ ion beam and the substrate temperature. The results are described below.

The dimensions of the height of the (400) tip of the thin polycrystalline Y ₂ O ₃ layer at different substrate temperatures are shown in FIG 10 shown.

A higher height of the (400) peak means a better orientation of the c-axis, namely the vertical axis of the thin polycrystalline Y ₂ O ₃ layer. It can be seen that the substrate temperature must be between 250 and 350 ° C and in a particularly preferred embodiment at 300 ° C, so that the vertical axis orientation of the thin polycrystalline Y ₂ O ₃ layer is ensured.

The dimensions of the height of the (400) tip of the thin polycrystalline Y ₂ O ₃ layer at different energy levels of the ion beam are out 11 seen.

11 shows that the vertical axis orientation of the thin polycrystalline Y ₂ O ₃ layer can be ensured by adjusting the energy of the ion beam between 100 and 300 eV, preferably between 125 and 175 eV, and in a particularly preferred embodiment on 150 eV. As 12 shows, the diagram of in 11 (400) peak produced from the (400) peaks measured on various Y ₂ O ₃ samples.

Polar plots of various thin polycrystalline Y ₂ O _{3 film} samples formed under different conditions with respect to the energy of the ion beam and the substrate temperature were prepared. Table 1 shows the grain boundary tilt angle determined from the polar diagrams of the various film-forming conditions. Table 1

In Table 1, the character x indicates that the pattern of the polar diagram is as in 9 showed rather distributed than it converged, and the angle of inclination of the grain boundary could not be measured. The results shown in Table 1 revealed that, to obtain the thin polycrystalline Y ₂ O _{3 film} having an inclination angle of the grain boundary below 30 degrees, it is necessary to have the energy of the ion beam between 135 eV and 175 eV and the substrate temperature between 250 and 175 350 ° C to adjust.

13 shows the relationship between the incident angle of the ion beam and the crystal orientation of the polycrystalline thin film when the thin polycrystalline Y ₂ O ₃ layer is produced by changing the angle of incidence of the ion beam, while all other conditions remain the same as described above.

It it is clear that a better crystal orientation will be achieved then can if the angle of incidence of the ion beam between 50 and 60 Degree is. In samples prepared under conditions outside this range no area could be found in which the pattern of the Polar diagram converges, and the full width could not be measured at half the maximum become.

Next, the oxide superconducting film was grown on the thin polycrystalline Y ₂ O _{3 film} by using a laser deposition apparatus of the type described in US Pat 8th is shown formed. A target of a superconducting oxide material of composition Y ₁ Ba ₂ Cu ₃ O _{7-x was} used. The deposition chamber was evacuated to an internal pressure of 1 × 10 ^-6 Torr (133.3 × 10 ^-6 Pa) and laser deposition was performed at room temperature. A 193 nm wavelength ArF laser was used to vaporize the target. Then, heat treatment was carried out at 400 ° C for 60 minutes in an oxygen atmosphere. A 1.0 cm wide and 100 cm long oxide superconducting element was obtained. Layer thickness (μm) 1 Jc (A / cm2) 4.0 × 10 ⁵ Ic (A) 40

Claims (2)

A method for producing a thin polycrystalline layer composed of oxide crystal grains whose crystal structure is a rare earth oxide type (C) described by any one of the following formulas: Y ₂ O ₃ , Sc ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O _3, and Lu ₂ O ₃ coated on the film-forming surface of a polycrystalline substrate wherein the inclination angles of the grain boundary between respective crystal axes of different crystal grains are kept at an angle of 30 ° along the plane parallel to the film-forming surface of the polycrystalline substrate, the polycrystalline substrate being brought to a temperature in the range of 250 to 350 ° C, and an ion beam of Kr ⁺ or Xe ⁺ ions or a beam combined from these ions is generated from an ion source, the energy of the ion beam being in a range of between 125 eV and 175 eV is set while the angle of incidence of the ion beam irradiating the film-forming surface of the polycrystalline substrate is between 50 and 60 degrees to the normal direction of the film-forming surface of the polycrystalline substrate when the particles formed by the same elements as the thin polycrystalline layer are exposed to the polycrystalline Substrate are deposited. Method for producing an oxide superconducting element a polycrystalline substrate, a thin one on the film-forming substrate surface the polycrystalline substrate formed polycrystalline layer and one on the thin one comprises polycrystalline layer formed superconducting oxide layer, being the thin one polycrystalline layer according to the method of claim 1 and the superconducting oxide layer after the deposition of the thin polycrystalline layer is formed.